Erika Shinohara enters high school burdened by insecurity stemming from past experiences as an outcast. This drives her to fabricate stories for peer acceptance, most notably claiming a relationship with popular classmate Kyouya Sata using a photo taken without his permission. The exposed lie forces her into an agreement where she acts as his subservient "pet dog" to maintain the charade, highlighting her people-pleasing nature and willingness to endure humiliation to avoid loneliness.

Physically petite, she possesses dark brown shoulder-length hair and brown eyes, favoring cute, feminine clothing. Her appearance evolves throughout the series, adopting a bob haircut and later, as an adult, a mature half-ponytail style. A notable habit involves sprouting imaginary wolf ears and a tail when lying, a manifestation linked to the "Boy Who Cried Wolf" fable that earns her the "Wolf Girl" nickname.

Her personality blends gullibility with flashes of determination. Often described as masochistic for tolerating Kyouya's harsh treatment, she demonstrates defiance when his cruelty crosses a line—throwing water at him after a fake confession or temporarily leaving upon overhearing disparaging remarks. She exhibits extreme jealousy concerning Kyouya and forms significant friendships, particularly with Ayumi Sanda, her sole initial friend aware of the fake relationship. Gluttony is a recurring trait.

Development occurs through persistent romantic pursuit. Despite Kyouya's initial rejection of her genuine feelings, she continues seeking him. Key milestones include her anguished confession in episode 3, enduring his emotional manipulation, and ultimately inspiring his softer side. Their relationship faces challenges from rival suitors: Kimura, who pursues her to hurt Kyouya, and Yuu Kusakabe, a shy classmate whose affection she rejects upon recognizing her enduring love for Kyouya. Kyouya eventually reciprocates, indirectly confessing during a White Day confrontation with Yuu and directly stating "I love you" at her birthday celebration.

She actively mends Kyouya's fractured familial relationships. Meeting his sister Reika and mother Hitomi reveals their divorce-related estrangement. Erika facilitates reconciliation, encouraging Kyouya to visit his mother more often and confronting Reika's insults, demonstrating fierce loyalty once their relationship becomes genuine.

The series concludes with her marriage to Kyouya, taking the surname Sata, and the birth of their daughter, Yuina. Professionally, she becomes a glassmaker, running a home-based enterprise crafting handmade glassware while embracing motherhood, solidifying her journey from a lie-dependent teenager to a self-assured adult.